DESCRIPTION (adapted from investigators' abstract): Group A streptococcal infections and their sequelae have occurred with a striking increase in rate and severity in the US during the past five years. It has been suggested that increased virulence in strains associated with severe infections is due to the appearance of strains producing increased amounts of certain extracellular toxins. The proposed studies will apply molecular biology techniques to strains associated with severe group A streptococcal infections, in order to establish a baseline of information for rapid identification of epidemiologically important strains. The specific aims of this study are : (1) to establish a physical and genetic map of the genomes of group A streptococcal strains associated with severe infections; namely M1, M3 and M18 serotype strains, and (2) to establish a rapid method for the identification of streptococcal strains of epidemiological significance using restriction fragment polymorphism (RPFL). Techniques such as pulsed gel electrophoresis (PFGE), polymerase chain reaction (PCR), and Southern blot hybridization will be employed to establish these maps. Based on already established DNA fingerprint analyses of the different M type strains, it is expected to find distinguishing features for each strain. This information will be exploited to develop rapid identification schemes for diagnostic purposes for use in central diagnostic and WHO laboratories.